Wireless-telegraph signaling system.



L. DE FOREST.

WIRELESS TELEGRAPH SIGNALING SYSTEM.

APPLICATION FILED DEC.6,19H.

Lmmws. Patented Apr.3,1917.

III

WWW/0O! Kw Mfm @511 W IJEE mt FOREST, 015 SAN FRANCISCO, CALIFORNIA, ASSIGNOR T0 RADIO TELEPHONE &; TELEGRAPH COMPANY, A CORPORATION OF DELAWARE.

WIRELESS-TELEGRAPH SIGNALING SYSTEM.

Specification of Letters Patent.

Patented Apr. 3, 191?.

Application filed December 6, 1911. Serial No. 664,135.

naling Systems, of which the following is a specification.

The object of my invention is to increase the output of wireless transmitting stations so that one station equipped with but one antenna system, and a single source of radiant energy, may perform the work of two or more transmitters, as by duplexing, triplexing, etc., and to simultaneously receive at a distant receiving station or stations, two or more messages from such transmitter.

Further objects, purposes and applications of my invention will be hereinafter more fully explained and claimed.

The invention consists substantially in the construction, combination, location and arrangement, all as will be more fully hereinafter set forth, as shown in the accompanying drawing, and finally pointed out in the claims. v

My invention will be described with reference to the drawing, accompanying and forming a part of this specification and in which Figures 1 and 2 represent diagrammatically two arrangements of transmitter circuits and Fig. 3 an arrangement of receiving circuits, whereby my invention may be carried into efi'ect.

In the drawing, A is an antenna system; L a helix or inductance in series with the antenna and earth connection E; D, D is a source of power. In Fig. 1, is shown at D a direct current source of potential suitable for energizingthe oscillating arc K. In

'Fig. 2, D is the secondary winding of a hi h tension transformer' H H are img 3 3 3 pedance coils, S 1s an interrupter or commutator, carrying on its periphery alternate.

conducting and non-conducting segments. K K are transmitting keys of the Morse type; p, 71,, 79 are points of contact on the inductance or helix L; b 6 are brush contacts for alternately making contact with the commutator or interrupter disk segments. G, in Fi .2 is a spark gap, prefera bly of the uenc ed spark type; C is a con.- dlenser in t e oscillatlng circuit containing the gap G. In Fig. 3, L L are separate inductances, preferably variable; L L,, are primary coils of receiving circuit transformers; C (1,, are capacities connected in shunt around L L and L respectively; 0,, and C are variable condensers connected to the terminals of the secondary coils L and L of the two receiving transformers; D and D are leads to suitable detectors and indi eating apparatus and as are commonly used in wireless telegraphy and telephony.

It is known that if during the receipt of an audible telegraph signal the transmitted current isinterrupted a great number of times per second the signals may still be read as certamly as though the current were continuous. It is feasible therefore to ra-pidly interrupt a train of radiated energy having a certain wave length and to momentarily substitute therefor another train having another wave length, and if at the receiving station or stations, suitable circuits are prepared, attuned respectively to each radiated frequency, then two or more messages may be simultaneously transmitted and received. It is only necessary that the interruptions and restorations of each wave train be at a sufficiently high, rate not to seriously interfere with the apparent continuity of each separate set of signals; and further that the several wave-lengths employed for the several messages be sufficiently di- 'vergent to enable the individual receiving len hs employed is ample to insure that eac receivmg apparatus will respond only to the signals intended for it.

In Fig. 1," I have shown a convenient method for applying my invention to the arc type of transmitter. -Here the antenna inductance L, is tapped at three points, p, p, and 79 If the contact 79,, is at, say the 10th turn of the helix (counting from the top or antenna contact) contact 72 at the 12th turn; and contact 79 at the bottom or 13th turn, then it is obvious that when brush 1),, is on an insulating segment of the intercircuit. Hence when the operators at keys is, and k, are resting, as between signals of the Morse code, the transmitter radiates a wave train whose wave length is determined by the constants of its antenna system including 10 turns of the helix Z. But each operator as he presses his key will cause waves of diiferent wave lengths to be radiated, one wave length being that determined by 12 turns of the helix, the other wave length being that determined by 13 turns. In no way, however, is it attempted. or possible in the invention here described to radiate energy defined by more than one wave length at the same instant.

In Fig. 2 the same principle is shown applied to a spark instead of an arc type of transmitter. In the figure the Morse keys are shown as of the make instead of the break contact type.

By this arrangement when both keys are open there is radiated a wave whose periodicity is determined by the entire helix. When brush b is on an insulating segment of the disk S, the circuit of key is, is held open and if during that period key k is closed a wave shortened by the cutting out of circuit of the turns of the helix between 1) and p, is radiated. Similarly when brush 1), is on an insulating segment the circuit of key is, is held open, and the length of the radiated wave is at that instant determined by the key 70,, provided that key chances to be closed at that instant.

Inasmuch as in the spark circuit shown in Fig. 2 we have two oscillating circuits, the constant circuit G, C, L and the antenna circuit A L E, which latter may have any of three natural periodicities, it is advisable that these two circuits be rather closely coupled, so that the antenna system will take a suflicient amount of energy from the oscillating circuit at whatever frequency the for mer may be attuned to.

In every case, to avoid excessive potentials and destructive sparking at key and interrupter contacts, it is advisable to take the taps ofi from the lowermost turns of the helix, near the earth connection.

Keys and brush contacts may be immersed in oil, or other means taken to prevent sparking, but if the potentials employed at the source are low, which is especially the case with the arc transmitter, such precautions are unnecessary.

The methods of receiving two or more wireless messages at the same station and even when using a common antenna are now so well understood by those skilled in the art as to require here no especial directions. The circuital arrangements illustrated in Fig. 3 I have found admirably adapted to the purpose in mind.

It is obvious that the methods hereinabove described for transmitting and receiving two sets of messages simultaneously may be extended to three or more, without departing from the scope of my invention.

It will be understood that many modifications may be made both in the apparatus and in the circuit arrangements herein described, and therefore I do not desire to be limited to the exact apparatus and systems which I have illustrated for the purpose oll more fully disclosing my invention.

I claim:

1. In a system for multiplex wireless signaling, a radiating antenna system, key controlled .circuits associated therewith, keys for controlling said circuits and means for automatically shunting said keys in succession.

2. In a system for multi-plex wireless signaling, a radiating antenna system, key controlled circuits associated therewith, keys for controlling said circuits, and means for automatically rendering each key operative in succession.

In testimony whereof I have hereunto set myhand in the resence of the subscribing witnesses, on this 29th day of November LEE DE FOREST. Witnesses:

EDITH W. BURNHAM, L. A. PODESTA. 

